1. Field
The present disclosure relates to an electric motor.
2. Description of the related technology
Generally a rotor of an electric brushless motor uses a permanent magnet and a rotor core of a ferromagnetic bulk or an electric steel sheet in order to form a magnetic circuit. However, when the permanent magnet rotor generates a rotation torque due to its interactions with an alternating magnetic field of a stator, there are vibrations generated in air gaps between the rotor and the stator. These vibrations can amplify to noise and/or be transferred to the load of the motor to cause damage or inefficiencies. Also, the weight of the ferromagnetic bulk or electric steel used as rotor core increases the weight of the motor and reduces efficiency in the application of the motor.